This invention relates to a method of metal oxide thin film cleaning using organic solvents to remove platinum chloride residue after dry etching of a platinum electrode.
Metal oxide thin films have a broad applications in ferroelectric and semiconductor devices. Platinum metal thin film is a commonly used material for the a device electrode. During device fabrication, the platinum metal thin film is subject to etching processes to form device patterns on silicon wafers. The best technique for platinum etching is a dry etching process, using chlorine-containing gases. During dry etching, the chlorine-containing gases react with the platinum metal to form non-volatile platinum-chloride-containing compounds, which removes platinum, but which leaves the platinum-chloride-containing compounds on other portions of the structure, or forms a fence along a photoresist side wall. Because these platinum-chloride-containing etching products are not volatile, they cannot be removed by a dynamic vacuum system. Wafer cleaning is necessary to remove the platinum-chloride-containing etching by-products from patterned metal oxide thin films.
A method of cleaning a metal oxide thin film on a silicon wafer, includes, in a first embodiment, dipping the wafer in an organic solvent, such as tetrahydrofuran for about 12 hours; drying the wafer in a nitrogen atmosphere; and stripping any photoresist from the wafer in an oxygen atmosphere under partial vacuum at a temperature of about 200xc2x0 C.
The second embodiment of the method of the invention includes dipping the wafer in a polar organic solvent taken from the group of solvents consisting of tetrahydrofuran and ether; applying ultrasound to the wafer while in the organic solvent for between about 10 minutes to 40 minutes; stripping any photoresist from the wafer in an oxygen atmosphere under partial vacuum at a temperature of about 200xc2x0 C.; dipping the wafer in a second organic solvent; applying ultrasound to the wafer for between about 5 minutes to 20 minutes; and drying the wafer in a nitrogen atmosphere.
It is an object of the invention to provide a method of cleaning the platinum chloride-containing dry etching residues from metal oxide pattern wafers.
This summary and objectives of the invention are provided to enable quick comprehension of the nature of the invention. A more thorough understanding of the invention may be obtained by reference to the following detailed description of the preferred embodiment of the invention in connection with the drawings.